JPS63264220A - Setting method for cage roll for electric welded tube - Google Patents

Abstract

PURPOSE:To prevent an edge buckling and a distortion and to stabilize a forming shape, as to a roll position of a cage roll, by estimating a deformating shape from an inlet and outlet shapes of the cage roll and by setting the cage roll to parallel to said estimated deformation shape. CONSTITUTION:The deformed shape in the cage is interpolated to set the roll 1 based on the shape of an inlet and outlet sides of the cage. A point on the outlet side 3 of the cage (X2, Y2, Z2) is interporated by an interpolating function, where X: distance from the cage inlet side 2, L: whole length of the cage and (n): shape parameter. More, when the shape parameter (n) changes, a deforming pattern becomes changeable. The shape parameter (n) is decided in an optimum value by calculation or an experimentation based on the outer diameter, thickness and strength. Furthermore, because the distortion is caused by a tortional moment in proportion to a moment arm, it is prevented by deciding the set angle of the roll to minimize the moment arm. In this way, the edge buckling and the distorsion is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for setting an ERW pipe cage roll.

In other words, it optimizes cage roll settings and prevents buckling, twisting, etc. when manufacturing tubular products by continuously forming a strip-shaped steel plate. Settings include downhill molding, which gradually lowers the height of the material through the initial breakdown, and roll gap settings to adjust the rolling reduction at the fin pass. However, for cage roles and cluster roles, a unified setting method has not been established due to the large degree of freedom in role setting and the large number of roles. In general, when forming with cage rolls, it is difficult to apply tension in the longitudinal direction, compressive force in the circumferential direction, etc., so that mainly bending deformation occurs. It is possible to distribute this bending mainly on the entry side, mainly on the exit side, or evenly. Another way of looking at bending distribution is to bend mainly the center on the entry side and mainly bend the edges on the exit side. A possible bending distribution is to bend mainly the edges on the entry side and mainly bend the center on the exit side, and the question is what kind of bending distribution is suitable for various conditions such as outer diameter and plate thickness. When determining the cage roll position repeatedly, it is difficult to set the cage roll position due to the large number of rolls.According to Ishikawajima Harima Giho 19-2 (1987), 67, as a conventional cage roll setting method, As shown in FIG. 8, there is a setting method in which the cage roll 1 only needs to slide in a straight line, assuming that the deformation is similar even if the outer diameter changes during molding in the cage. in this way,
This method has the following problems.

(a) If the outside diameter of the pipe changes, the length of the equipment does not change, so the total length of the cage roll remains unchanged.If the ratio of the outside diameter of the pipe to the length of the cage roll is different, the deformations cannot be considered similar. Therefore, for both tubes with a smaller outer diameter and tubes with a larger outer diameter within the range that can be manufactured with the manufacturing equipment,
It is difficult to find optimal settings that can be shared.

(b) If the wall thickness and strength change, the rigidity of the material and the progress of plastic deformation will change, so the optimal roll setting position will change, but this roll setting method does not take into account the effects of wall thickness and strength. Therefore, if the wall thicknesses differ greatly or the strengths of the materials differ greatly, it is difficult to find an optimal setting that can be used in common.

(C) A setting method that is advantageous for preventing twisting is not clear.

Therefore, in manufacturing ERW pipes using conventional roll settings,
It is not possible to prevent buckling in the manufacture of tubes with an infertile wall thickness-to-outer diameter ratio (t/D), and torsion in the manufacture of tubes with a large wall-thickness-to-outer diameter ratio.

[Problem that the invention seeks to solve]

With conventional technology, there is no method for setting cage rolls that can prevent buckling in thin materials, poor forming in thick materials, and twisting over a wide range of outer diameters, plate thicknesses, and strength ranges. . Therefore, over a wide range of outer diameters, plate thicknesses, and strengths, an optimal cage roll method is used to prevent buckling in thin materials, twisting in thick materials, and defective forming.

[Means for solving problems]

In the present invention, as shown in FIG. 1, the deformed shape of the tube is predicted from the shapes of the cage entrance side 2 and the cage exit side 3, and the cage roll is set so as to follow the predicted deformed shape. In the breakdown used in the pre-forming stage and the fin pass used in the post-forming stage, the molding shape is mainly determined by the roll hole shape, but in cages the contact area between the material and the roll is small compared to the material length. It is difficult to determine the cross-sectional shape of a one-hole type. However, K, which strictly determines the deformed shape in order to find the optimal setting value for the cage, is
It is necessary to perform calculations or experiments to three-dimensionally bend the plate in the cage with each cage roll to determine the roll setting position.

The present inventor interpolated the deformed shape inside the cage from the shape of the cage entrance side (breakdown shape before cage molding) and the shape of the cage exit side (fin path shape after cage molding), and created a structure to follow this deformed shape. It was discovered that even when the roll was set, the difference between the actual deformed shape and the deformed shape used for the roll setting was small. Figure 2 (a), (b),
((ri) shows the deformed shape interpolated from the deformed shape on the cage entry side and the deformed shape on the cage exit side, and the actual deformed shape. The symbol shown is the actually measured deformed shape.In other words, since it is difficult to measure the entire deformed shape, the actual deformed shape is calculated from the opening 4 width B1 full width W1 total height H of the blank plate and the interpolated shape. Compare with the calculated 9B, W, H (Fig. 2 (ψ)).Fig. 2 is a comparison of the actually measured shape in the cage and the interpolated shape, using the cage entrance stand as the reference point for the longitudinal distance. Note that 2,4°6 of n in the figure indicates the shape parameters described later, and even if the shape parameters change variously, the deformed shape (interpolated shape) used for roll setting and the actual deformed shape are sufficient. It can be seen that they match with a high degree of accuracy. Therefore,
Instead of calculating or experimentally determining the deformed shape by changing the setting position of the cage roll, and determining the setting value of the cage roll so that the deformed shape is optimal, the present invention conversely determines the deformed shape inside the cage. The cage can be set based on the deformed shape of the cage.

Figure 3 specifically shows the interpolation method for the deformed shape.The interpolation function is used to calculate the spatial locus between corresponding positions in the width direction in the shape of the cage entry side and the shape of the cage exit side. Determine by interpolation. As an example of an interpolation function, F (x)=sin (x/2(x/L)n) (
1) X: Distance from the cage entrance side L: Total length of the cage n-: The following description will be made using the shape parameter. As shown in FIG. 3, the corresponding points on the cage entry side in the width direction (xt, Yt).

Zl) oyoU';r -Side1iinoA (xtt
Yt-Zt) is interpolated using the interpolation function shown in equation (1).

For example, for Y, Y = Yt + FQQ・(Yt − Yt)
(2). Furthermore, as shown in Fig. 3, when the shape parameter included in the interpolation function changes, the shape of the cage changes from D, which is uniformly deformed within the cage (when n is small like 1 to 2). The pattern of deformation can be changed so that deformation is mainly performed in the latter half (when n is large, such as 4 to 6). In addition.

In addition to the form of the interpolation function shown in equation (1), G(x)=(x/L)r'((x/L-1)-+DX:
Distance from the cage entry side L: 2 Cage total length n, m: Interpolation is also possible using polynomials such as shape parameters, or those using trigonometric functions in other forms 0 Such deformation within the cage To give the shape, the outer diameter, wall thickness, strength, etc. of the steel pipe must be considered. This is because when forming ERW tubes, cage rolls mainly perform the forming process by bending.1. The bending stiffness is influenced by the outer diameter, wall thickness, and the progress of bending, and as the bending progresses, the strength goes beyond the elastic range and enters plastic deformation, and the formula for this plastic deformation is Since platforms vary in strength, strength is also a factor governing deformation in cage rolls. Therefore, when setting cage rolls, it is necessary to consider how best to proceed with deformation depending on the outer diameter, wall thickness, strength, etc., and to set a large number of cage rolls.
Optimal cage setting conditions can be determined by determining the shape parameter n in equation (1) by calculation or experiment so as to have an optimal value in consideration of the outer diameter, wall thickness, and strength.

Therefore, the shape parameter n is n=f (D, t, σy) (3) n: shape parameter D: outer diameter t: wall thickness σY: material strength, and the optimal value for outer diameter, wall thickness, and strength is calculated. constant table or
The role is set by having the function of equation (3). The value of the shape parameter is determined so that buckling does not occur for thin walls, and that the molding reaction force in the cage is small for thick walls. Since the restraint of the material by the cage rolls is small, damage is likely to occur.The twisting is thought to be due to a twisting moment generated due to the difference in forming reaction force between the left and right cage rolls.To prevent twisting in the cage, It is necessary to reduce the torsional moment.

The torsional moment is determined by the difference between the left and right molding reaction forces, X moment arm. Among these, the difference in molding reaction force between the left and right sides is due to variations in the materials, differences between the left and right sides in the pre-molding stage, etc., but the reaction force of the cage can be reduced by the setting method using the interpolation function described above. This setting method is advantageous in reducing the size of the legs and torsion. On the other hand, for the moment arm, the cage setting method described above determines the shape of the cross section at the position of each cage roll. The moment arm of the moment can be found. FIG. 4 shows the cross-sectional shape of the cage determined from the shape of the cage entrance side and the shape cam of the cage exit side, and the position of the cage roll, and the moment arm can be determined geometrically. Therefore, in order to prevent twisting, the deformed shape inside the cage is predicted by interpolating the shape of the cage entrance side and the shape of the cage exit side at the position of each cage roll from the entrance side to the exit side of the cage. , if the set angle of the roll is determined so that the moment arm has no play, then
It was discovered that twisting can be prevented.

〔Example〕

Next, examples of the present invention will be described.

FIG. 5 shows a nine-roll molding apparatus used in the experiment, in which a breakdown stand 4 was used in the early stage of molding, a cage roll 1 was used in the middle stage of molding, and a fin pass 5 was used in the latter stage of molding. As an example of forming a thin material, the plate thickness is 0.8mm and the outer diameter is 76mm.
It was molded using a steel plate of 3 vm (t/D=1 inch). FIG. 6 shows the relationship between the roll setting parameters and the magnitude of buckling occurring at the edge of the thin-walled tube. The degree of buckling of the edge portion was evaluated by steepness (λ=h/p) using buckling pitch ω) and buckling wave height -g (h). In the case of this molding condition, molding was performed while changing the shape parameter (3) of the interpolation function (1) from 2 to 6. Buckling does not occur when the shape parameter n is set to 2 to 4, but buckling occurs when the shape parameter is set to 6, and the steepness of buckling at the edge portion becomes large.

Therefore, it can be seen that the shape parameter should be set to 2 to 4 under these molding conditions. It can be seen that if the deformed shape is determined in consideration of the wall thickness, outer diameter, and strength from the shape of the cage entrance side and the cage exit side shape by the setting method of the present invention, the effect of preventing edge buckling is large.

As an example of forming thick material, plate thickness is 8W11, outer diameter is 76.3cm.
(t/D=10%) was molded using a steel plate.

FIG. 7 shows an example of molding in which the support angle of the roll setting can be changed to three levels: large, medium, and small moment arms. When the moment arm determined from the deformed shape is made smaller (
With the setting method of the present invention), no twist occurs, but if the moment arm is large, twist occurs. It can be seen that the cage setting method of the present invention is highly effective in preventing twisting.

〔Effect of the invention〕

By adopting the method of the present invention, even when forming tubes with a wide range of outer diameters, wall thicknesses, and strengths, edge buckling and twisting are prevented, and the formed shape is stable and good. can do. In addition, it exhibits an excellent effect of stably improving the quality of welded parts.

[Brief explanation of the drawing]

FIG. 1(a) is an explanatory diagram showing the cage setting method according to the present invention, FIG. 1(a) is a cross-sectional view of part A in FIG.
, (b), (((d) is an explanatory diagram showing the deformed shape predicted from the shape of the cage entry side and the cage exit side and the actually measured deformed shape, FIG. 3(a) is an explanatory diagram of the shape. φ) is an explanatory diagram showing an interpolation method of the deformed shape inside the cage according to the shape of the cage entrance side and the shape of the cage exit side, and an example of the function used for the interpolation. An explanatory diagram showing a method of determining the torsional moment arm and a method of determining the low setting angle based on the deformed shape inside the cage,
Fig. 5 is an explanatory diagram of the roll forming apparatus used in the implementation of the present invention, Fig. 6 is an explanatory diagram of an example in which buckling is prevented in thin-walled materials, and Fig. 7 is an explanatory diagram of an example in which buckling is prevented. FIG. 8 is an explanatory diagram showing that twisting can be prevented in this embodiment. FIG. 8 is an explanatory diagram showing an example of a conventional cage setting method. Figure 1 (a) (b) Figure 3 (a) x/L Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] When manufacturing a steel pipe by roll forming a steel strip using a cage roll between a breakdown roll and a fin pass roll, the roll position of the cage roll is changed from the shape of the entrance side of the cage roll and the shape of the exit side of the cage roll. A method for setting an electric resistance welded tube cage roll, comprising predicting the shape in advance and setting the cage roll so as to follow the predicted deformed shape.